Department of Radiology, Royal Marsden Hospital, Downs Rd, Sutton SM2 5PT, UK.
AJR Am J Roentgenol. 2011 Jun;196(6):1351-61. doi: 10.2214/AJR.10.5515.
Diffusion-weighted MRI is increasingly applied in the body. It has been recognized for some time, on the basis of scientific experiments and studies in the brain, that the calculation of apparent diffusion coefficient by simple monoexponential relationship between MRI signal and b value does not fully account for tissue behavior. However, appreciation of this fact in body diffusion MRI is relatively new, because technologic advancements have only recently enabled high-quality body diffusion-weighted images to be acquired using multiple b values. There is now increasing interest in the radiologic community to apply more sophisticated analytic approaches, such as those based on the principles of intravoxel incoherent motion, which allows quantitative parameters that reflect tissue microcapillary perfusion and tissue diffusivity to be derived.
In this review, we discuss the principles of intravoxel incoherent motion as applied to body diffusion-weighted MRI. The evidence for the technique in measuring tissue perfusion is presented and the emerging clinical utility surveyed. The requisites and challenges of quantitative evaluation beyond simple monoexponential relationships are highlighted.
扩散加权磁共振成像在人体中的应用日益广泛。基于脑科学的科学实验和研究，人们已经认识到一段时间，MRI 信号与 b 值之间的简单单指数关系计算表观扩散系数不能完全反映组织行为。然而，在体部扩散 MRI 中意识到这一事实相对较新，因为技术进步最近才能够使用多个 b 值获得高质量的体部扩散加权图像。现在，放射学界越来越有兴趣应用更复杂的分析方法，如基于体素内不相干运动原理的方法，这些方法可以得出反映组织微血管灌注和组织扩散性的定量参数。
在这篇综述中，我们讨论了体素内不相干运动原理在体部扩散加权磁共振成像中的应用。介绍了该技术在测量组织灌注方面的证据，并调查了其新兴的临床应用。突出了超越简单单指数关系的定量评估的要求和挑战。
